Electrical devices often have integral power supplies which can be at least partially powered by an external power source, for example mains electricity in the case of a laptop computer. If the integral power supply fails, the device stops operating. This is a particular problem in cable television (CATV) and broadband networks where many active devices with integral power supplies are used, such as optical nodes, amplifiers and the like, and all signals going to and from customers subscribing to the network are routed via these devices.
If the integral power supply of any one of the CATV active devices fails, the network connection and service to the subscriber also fail. The integral power supplies are typically designed with the use of electrolytic capacitors which have a low “Mean Time Between Failures” (MTBF) compared to all other components used in the active devices. Thus the integral power supply is likely to fail before other components fail.
When the active device fails, there is always a signal interruption for the customer during the replacement. Analogue/digital TV, triple play Internet and video on demand services routed through the CATV network are temporarily unavailable until a technician has finished the replacement and configuration of the active device. It is very important to have a network that can be updated and configured without the customers' cable service being interrupted.